I had great success using trailers of the "lawn service" type (low to the
ground, steel trailers with ramps) 
http://www.acetrailersales.com/images/lawn_th614ls.jpg
fitted with the sort of heavy-duty chain-link fencing one would use to make
a "dog run" at a kennel.  

The "roof" must be reinforced with extra cross-members. The Blue Ridge
Mountains are infested with (small!) black bears, so this is very much an
east-of-the-Rockies
solution.  Removing trailer wheels so that the trailer sits flat on the
ground and padlocking the ramp/door also kept humans at bay.

The advantage of this "passive" approach is that there is no equipment to
maintain or break down.  

If not for the premium price commanded by sourwood honey, this would have
never paid off.  Sourwood honey requires one to place hives in remote
locations where either fires or clear-cuts took place 4 or 5 years ago, so
one is placing one's hives smack in the middle of the bears' turf.

My reading of the relevant documents does not permit me to exclude bears
from the general principle "Thou Shalt Not Kill".

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